Investigators carried armfuls of concrete and rubble from an excavation site at a building in downtown Manhattan.

"We, along with (the New York Police Department), are going to be methodically going through the basement area, into the concrete, into the drywall, and looking for evidence," said FBI spokesperson Tim Flannelly. "We do have good probable cause to be here."

Investigators plan to continue digging in the basement through the beginning of next week, reports CBS This Morning Senior Correspondent John Miller.

The 33 year old case was reopened after cadaver dogs detected the scent of human remains at the site.

Seventy-five-year-old Othniel Miller used the space as a workshop back then. A neighborhood handyman, Miller knew Etan and his family. He denies any involvement with the child's disappearance.

"After this case," pointed out NYPD spokesperson Paul Browne, "there became a much more protective environment around children, generally."

This was the case that, years ago, made parents reassess places they once judged safe -- like their very own streets and neighborhoods, Miller notes.

The case was, says Cohen, the first "in a long, long time that just captured the imagination of, first this city, and then the rest of the country, and ultimately the world."

Cohen, author of "After Etan: the Missing Child Case that Held America Captive" and a former producer for CBS News and ABC News, said, "I think there was a time before Etan when kids played in the street and you walked to the bus stop by yourself, those two blocks, and then there was an after-Etan. After that, people knew that it could happen. And once you know that it can happen, then you think maybe it will happen. It changed everything.

"I think that, out of this case, and then a few very few high-profile cases that followed, a whole movement began. And there were congressional hearings, there were all kinds of initiatives for tracking children in a better way, and ultimately, things like the National Center for Missing and Exploited Children were created. So now, there's a new awareness.

"And there's some divisiveness about this. On the one hand people say, 'We know the risks now.' On the other hand, people say, 'We've taken away the freedom of our children. And people shouldn't be so nervous and worried and isolating."

The Patz family, Cohen says, is "very reserved. They've been through this for 33 years. They have seen so many cases, so many moments where the hopes were up, they've got the guy, you know, they've got the break in the case. And then it doesn't happen. So, you know, I think that -- I speak to Stan Patz, and I know he's grateful the New York district attorney has been willing to make this kind of commitment and put resources into this, but he's gonna wait and see."

To see the complete John Miller report and Lisa Cohen interview, click on the video in the player above.